Vibration absorbing handle for rock drills



Fell 24, 1953 J. H. ANDERSON VIBRATION ABSORBING HANDLE FOR ROCK DRILLS Filed June 16, 1950 INVENTOR JBAYMES 4PLANDERSON HIS ATTORNEY.

.motive fluid to the tool.

Patented Feb. 24, 1953 UNITED STATES PATENT oFF-ics VIBRATION ABSORBING HANDLE FOR ROCK DRILLSIv 7 Claims.

l This invention relates to rock drills, and more particularly to devicesforabsorbing the vibrai tion resulting from the operation of rock drills v of the hand-held type.

Thework of operating a percussive tool is very fatiguing because the vibrations set up by the tool are transmitted to the operator through the handle. As a consequence, the amount of work a man can do decreases materially the longer he operates the tool. If the operator could be isolated from the tools vibration he would then be protected from the fatigue caused by such vibration.

It is, accordingly, an object of this invention to isolate the operator from the vibrations set up by the tool.

Another object `of this invention is to construct a device to absorb the vibration normally transinitted to the handle.

Other objects will be in part obvious and in part pointed out hereinafter.

In the drawings in which identical reference numerals refer to similar parts,

Figure l is a side elevation showing a. portion of a percussive tool constructed in accordance with the practice of this invention,

`Figure 2 is a sectional view .taken along the A line 2 2 in Figure 1 looking in the direction of the arrows, and

YFigure 3 is a sectional View taken along .the line 3 3 in Figure 2 looking in the direction of the arrows.

Referring now to the drawings tor a detailed description of the invention, I!) designates the back head portion of a percussive tool. YThe back head I!) is joined to the cylinder barrel II (partly shown) by a pair of bolts I2 and is .provided with a valve I 3 to throttle the sup-ply of In accordance with the practice of this invention the back head II] is further p-rovided with a projection I4 which serves as a pivot post for the handle assembly I5 of the tool.

The hand-gripped portion of the handle assembly l5 is formed by a long bolt I5 having cylindrical sections I1 mountedl thereon. A pair of lever arms 2E), having bores 2I at one -end to receive the bolt I6, are positioned on the bolt It intermediately of the sections I1 and connect the hand-gripped portion of the handle assembly I5 with the pivot `post I4. Accordingly, the lever arms 2i] lare spaced on the bolt I6 so that the inner side surfaces 22 of the lever arms lie on opposite sides of the pivot post I4. The cylindrical sections I'I and lever arms 2U are locked on 2 the bolt IB by anut I8 .and .washer IS threaded onto one end of the bolt I B.'

The lever arms 2i) are joined to the pivot post i4 4by a torsional coupling which preferably takes the form shown inthe drawings in which each of the lever arms l2Il is each provided with a bore 23 having a series of serrations in its periphery.

A similarly serrated bore. 24 is also .provided in the. pivot post I4, and when the lever arms 2d are positioned alongsidethe pivot post the bore therein is in concentricalignmentwith the bores 23 in the lever arms 20.

Rubber liners e-SI are inserted into the bores 23 of the lever arms .2G and into the bore 24 of the pivot post I4; the liners in the lever arms being designatedl by the numeral 3] and the liner in the pivot post by the numeral Si. Bonded to the out-er surf-ace of -the liners Sli-3| are bushings 2'I having their outer surfaces serrated to match the serrated .bores 23 in the lever arms A2t and the pivot post I4. `When the liners .it and SI and bushings Av2I are inserted into the bores 23 and 24 the serrated bushings 21 interlock with ythe serrations in the bores to xedly position the n to the lever arms 20 and pivot .post I4.

For the purpose of joining the lever arms 2t to the. pivot post Ill-.the liners SI1-3| are eac-l1 provided with a central bore `25 into which a rod 28 is inserted and bonded to theinner surface thereof. VEach of the end portions of the rod 23 is joined to a liner in -ajlever arm while the Icentral portion of the rod 28 is joined to the liner 3l 4in the pivot post I4. The nod 28 thus provides a means for transmitting torque from one Vliner to another.

In the normal operation of the invention the handle assembly is held in working position, as Ishown, in the dr-awingaby the operator. The valve I3 is opened to admit iiuidto the actuating mechanism (not shown) of the tool to cause `the tool to operate. Operation of the tool causes vibrations which result in axial thrusts of the tool casing Ii and pivot post I4. Since the handgri-pped portion of the handle assembly i5 is held by the operator the lever arms 2li pivot about the pivot post I4 thereby producing a torqueon the liners v'IIB- .3 I.

The outer surfaces of the liners tu rotate with the lever .arms 2t while the inner surfaces are rotated to a lesser extent causing the liners Sii to twist or deiiect torsionally. At the same time the rod 28 rotates with the inner surfaces of the liners 30 and since it is bonded to the inner surface of the liner 3| in the pivot post causes 3 this inner surface to rotate to the same extent. Rotation of this surface causes the liner 3l to twist or deflect torsionally because the outer surfaces are xedly positioned in the pivot post I4. Thus, by the manner set forth, is the vibration of the tool absorbed in the torsional deection of the liners 30-3I.

By employing liners in both the lever arms and the pivot post the applicant achieves a construction which is Very effective in absorbing vibration because by placing a large liner in the pivot post in series with two smaller liners in the lever arms the effective spring length is doubled over that of a construction employing only one liner. The deection for a given load is also doubled and this greater deflection results in more effective isolation of the vibration from the handle of the tool.

In order to obtain effective absorption of the tools vibration it is desirable to have the liners pre-stressed to a value approximating the range of values encountered when the tool is in operation. For this purpose the lever arms are mounted on the outer liner bushings 2l in a position other than the normal operating position. The lever arms 20 are then rotated in a clockwise direction in the drawing to the normal operating position in which the liners -3l will have been twisted to an extent to place the liners 3U--3I under a stress approximating those stresses to be encountered in operating the tool. It will be readily seen that the serrations on the bushings 21 and in the bores 23 of the lever arms 20 allow the lever arms to be mounted on the bushings in any position necessary to obtain the desired amount of stress in the liner.

A mechanism 32 is provided on the back head I0 for holding the handle assembly l5 in the normal operating position and comprises a hooking member 33 slidably mounted on the back head I0 and having hooks 34 projecting upwardly and outwardly from the member 33 for engagement with hooks 35 depending from the lever arms 20. The hooking member 33 is secured to the back head l0 by means of a screw 36 projecting through a slot 31 in the member 33. A washer 39 on the screw 36 fastens the hooking member 33 to the back head I0. Whenever it is desired to release the handle assembly I5 the screw 36 is loosened to allow the hooking member 33 to be slidably moved out of engagement with the hooks 35 depending from the lever arms 20.

I claim:

1. A handle for a percussive tool having a casing, comprising a hand-gripped portion, a lever arm for the hand-gripped portion, a resilient member on the lever arm, a resilient member on the casing, and a connection between the resilient members for transmitting torque from one member to the other member.

2. A handle for a percussive tool having a casing, comprising a hand-gripped portion, a lever arm for the hand-gripped portion, a resilient member carried by the lever arm, a resilient member carried by the casing, means for preventing rotary movement of the members with respect to the lever arm and the casing, and a connection between the members for transmitting torque from one member to another.

3. A handle for a percussive tool having a casing, comprising a hand-gripped portion, a lever arm on the hand-gripped portion, a resilient member twistably secured to the lever arm, a resilient member twistably secured to the casing, and a connection between the resilient members for transmitting torque from one member to another.

4. A handle for a percussive tool having a casing, comprising a hand-gripped portion, a lever arm on the hand-gripped portion having a bore, a resilient liner in the bore in the lever arm, a bore in the casing, a resilient liner in the lastmenticned bore, means for preventing rotation of the liners in the bores of the casing and the lever arm, and a connection between the resilient liners secured thereto, said connection being rotatable with respect to the lever arm and casing.

5. A handle for a percussive tool having a casing, comprising a hand-gripping portion, a pair of lever arms fastened to the hand-gripped portion, a bore in each of the lever arms, a projection on the casing adapted to extend between the pair of lever arm and having a bore in coaxial alignment with the bores in the lever arms, rubber liners in all of the bores, means .for preventing rotation of the liners in the bores, and a rod extending into the liners and being securely joined thereto to transmit torque from one liner to another.

6. A handle for a percussive tool having a casing, comprising a hand-gripped portion, a pair of lever arms fastened to the hand-gripped portion, a bore in each of the lever arms, a projection on the casing adapted to extend between the pair of lever arms and having a bore in coaxial alignment with the bore in the lever arms, bushings selectively and interlockingly positioned in all of the bores, rubber liners in the bushings, and a rod extending into the liners and securely joined thereto to transmit torque from one liner to another.

7. A handle for a percussive tool having a casing, comprising a hand-gripped portion, a lever arm fastened to the hand-gripped portion, a bore in the lever arm having a plurality of serrations in the periphery of the bore, a bore in the casing having a plurality of serrations in the periphery of the bore, bushings having serrated outer surfaces selectively and interlockingly positioned in the bores, rubber torsion levers bonded to the inner surfaces of the bushings, and a rod bonded to the inner surfaces of the rubber liners for joining the torsion liners and transmitting torque from one liner to the other.

JAMES H. ANDERSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,062,817 Noble Dec. 1, 1936 2,101,869 Noble Dec. 14, 1937 FOREIGN PATENTS Number Country Date 122,752 Austria May l1, 1931 

